Baird et al., Int. J. Cancer, 19, 403-417 (1977), have reported on binding assays of a radioviral ligand prepared from whole murine leukemogenic virus with mouse thymus lymphoma cells. The percent binding of the radioligand to presumptively receptor positive cells was low (.congruent.10%) and the amount of radioligand added to obtain significant uptake was high (&gt;100,000 cpm). This type of result obtained in a whole virus radioligand-receptor cell binding study is quite different from that in the use of radiolabeled virus in radioimmunoassay procedures based on antigencity, where ligand binding activity or sensitivity is generally higher.
Similar to the whole virus cell receptor study, Fowler et al., J. Virol., 24, 729-735 (1977), have reported studies using radiolabeled surface glycoprotein of murine leukemia virus as a cell binding ligand. Only a portion (15-40%) of the antigenically competent radiolabeled glycoprotein was bound to susceptible murine cell lines.
The above indicates an inability to prepare an effective cell binding radioviral ligand which would not only be a useful antigenic substance but could also be used to quality and quantify cell receptors.